Taxonomic distribution of proteins containing RPOL_N domains

The tree below includes only several representative species and genera. The complete taxonomic breakdown of all proteins containing RPOL_N domains can be accessed here. Click the counts or percentage values to display the corresponding proteins.

Structural basis for the transition from initiation to elongation transcriptionin T7 RNA polymerase.

Yin YW, Steitz TA
Science. 2002; 298: 1387-95

To make messenger RNA transcripts, bacteriophage T7 RNA polymerase (T7 RNAP)undergoes a transition from an initiation phase, which only makes short RNAfragments, to a stable elongation phase. We have determined at 2.1 angstromresolution the crystal structure of a T7 RNAP elongation complex with 30 basepairs of duplex DNA containing a "transcription bubble" interacting with a17-nucleotide RNA transcript. The transition from an initiation to an elongation complex is accompanied by a major refolding of the amino-terminal 300 residues.This results in loss of the promoter binding site, facilitating promoterclearance, and creates a tunnel that surrounds the RNA transcript after it peels off a seven-base pair heteroduplex. Formation of the exit tunnel explains theenhanced processivity of the elongation complex. Downstream duplex DNA binds tothe fingers domain, and its orientation relative to upstream DNA in theinitiation complex implies an unwinding that could facilitate formation of theopen promoter complex.

Structure of T7 RNA polymerase complexed to the transcriptional inhibitor T7lysozyme.

Jeruzalmi D, Steitz TA
EMBO J. 1998; 17: 4101-13

The T7 RNA polymerase-T7 lysozyme complex regulates phage gene expression during infection of Escherichia coli. The 2.8 A crystal structure of the complex revealsthat lysozyme binds at a site remote from the polymerase active site, suggesting an indirect mechanism of inhibition. Comparison of the T7 RNA polymerasestructure with that of the homologous pol I family of DNA polymerases revealsidentities in the catalytic site but also differences specific to RNA polymerase function. The structure of T7 RNA polymerase presented here differs significantlyfrom a previously published structure. Sequence similarities between phage RNApolymerases and those from mitochondria and chloroplasts, when interpreted in thecontext of our revised model of T7 RNA polymerase, suggest a conserved fold.